It has been a longstanding observation that weight loss is a common problem in patients with chronic obstructive pulmonary disease (COPD) and that this has an adverse effect on prognosis. We have previously reported the association of significant malnutrition with emphysema and noted that the degree of malnutrition correlated with some measures of pulmonary function. Our preliminary studies suggest that malnutrition has an adverse effect on ventilatory muscle strength. In addition, it is our clinical impression that weight loss and decrement in pulmonary function are not monotonic in these patients, but often occur as a "step change." In a recently completed pilot study, we have demonstrated that in a controlled setting these patients will gain weight and that the weight gain is associated with improvement in peripheral and ventilatory muscle strength. Using a carefully controlled and randomized study design and monitored nutritional supplementation, we will determine the physiologic effects of nutritional repletion on the ventilatory function of malnourished emphysema patients. Complete pulmonary function testing, exercise and 12 minute walk performance will be measured before and after nutritional intervention. In order to evaluate the effects of malnutrition and subsequent nutrition therapy on ventilatory muscle strength and function, we will measure maximal trans-diaphragmatic, inspiratory and expiratory pressures before and after nutritional supplementation. We will also measure handgrip strength before and after nutritional intervention as an index of overall muscle strength. By careful interviewing and close follow-up, we will determine if nutritional therapy improves the quality of life and reduces the requirements for hospitalization of these patients. In summary, we hope to define the role of malnutrition in the pathogenesis of ventilatory dysfunction in emphysema and to determine the effectiveness of nutritional support in reversing this dysfunction. From the data collected in this investigation, it may be possible to develop a strategy by which nutritional intervention can be developed for COPD patients. If as our pilot study suggests, muscle strength can improve with nutritional intervention, perhaps this could decelerate the predictable decline of ventilatory function in these patients.